JP3789862B2 - Link status notification device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a protection line setting technique for improving the reliability of a router or an optical router network controlled autonomously and distributedly.
[0002]
[Prior art]
Due to an increase in data communication traffic such as the Internet, the introduction of node devices having a throughput of Tbit / s at present and 10-100 Tbit / s or more in the near future is being promoted. The main communication protocol on the Internet is the TCP / IP protocol. The IP protocol basically has a function of dividing communication data into packets and a function of giving a source and destination address to the divided packets, and provides a so-called best effort service in which quality is not guaranteed. Is.
[0003]
[Problems to be solved by the invention]
However, with the widespread use of the Internet, it is beginning to require that the Internet have the ability to transfer real-time data such as images and sounds with high quality from the user side. On the other hand, there is an increasing need for Internet service providers to provide high-quality Internet services while responding to the rapid increase in communication traffic, which is said to be twice in half a year.
[0004]
However, as shown in FIG. 16, in the network controlled by the current IP protocol, the guarantee of the connectivity of the communication traffic to be transferred is not strict and the reliability for the equipment failure is very low. A function to define a protection line that must be set in the relay system, and also a means to efficiently reduce the amount of protection line equipment to be defined, automatically uses a shared protection line that shares multiple active lines with a single protection line. The function to set to is not yet realized.
[0005]
The present invention provides a means for solving the above-described problems, and in a network controlled by the IP protocol, the amount of equipment required for setting up a protection line can be effectively suppressed, and an equipment failure can be prevented. An object of the present invention is to provide a link state notification device capable of constructing an autonomous distributed control network that realizes stable operation.
[0006]
[Means for Solving the Problems]
As shown in FIG. 1, the present invention adds a function for each node to set not only the working line but also the route of the protection line in an autonomous and distributed manner in a network controlled by the IP protocol.
[0007]
As the means, the present invention applies the following two techniques. The first is SRLG (Shared Risk Link Group (reference: IETF Internet draft draft-ietf-ipo-framework-01.txt)). In this specification, SRLG is referred to as a risk classification number. This is a technique for managing a failure of each link or node device as a scenario number, and predetermining a backup line setting route for relieving an active line for each failure scenario.
[0008]
The second is a technology for publishing link information, which is necessary to determine the backup line setting route. For example, the OSPF and IS-IS protocols have a function of notifying the entire network area of the state of each link existing in the network area (reference: Mastering TCP / IP application edited by Phillip Miller, ohm company ISBN4-274- 06256-2).
[0009]
The present invention is based on the above two technologies and extends the functions of routing protocols such as OSPF and IS-IS protocol. As shown in FIG. 2, the extended function of the present invention is a technique for notifying the configurable bandwidth of a backup line set for each link, that is, the amount of link resources that can be set for a backup line, and for each risk classification number. The amount of resources that can be backed up is announced. In particular, the present invention aims to realize an appropriate backup line setting while suppressing the amount of notification information.
[0010]
In more detail, the SRLG of the link managed by the node and the SRLG of the link through which the working path backed up by the shared spare band passes is searched for the SRLG that can be backed up by the link and the SRLG that cannot be backed up. By publishing this SRLG information to other nodes, each node can grasp the SRLG information over the entire network, and setting the protection line based on the grasped SRLG information is necessary for setting the protection line. It is possible to construct an autonomous decentralized control network that realizes a stable operation against an equipment failure tolerance while effectively suppressing the amount of equipment to be installed.
[0011]
That is, the present invention is a link status notification device, and the feature of the present invention is that the network topology and the link usage status are grasped based on the announcement from other nodes, and the grasped network topology and link utilization are determined. A link bandwidth allocation management database that is provided in a node that selects a transfer route of communication traffic that passes through itself based on the status, and that manages a bandwidth allocation status of a link that is to be managed based on the announcement, and this link bandwidth allocation management Backup risk for managing the SRLG of the link through which the working path backed up by this shared spare band is input from the database by inputting information on the shared spare band, which is a backup band that can be used to back up multiple links set for the link in common Classification number management database and database of the two parties The backup possible risk classification number management database that searches and registers and manages the SRLG that can be backed up and cannot be backed up from the link, and the SRLG information registered in this backup possibility risk classification number management database is announced to other nodes. SRLG notification means.
[0012]
In this way, each node in the network can grasp the SRLG of the entire network by notifying other nodes of the risk classification number that is SRLG. As described above, SRLG is a technology that manages the failure of each link or node device as a scenario number and decides in advance the setting path of the backup line for relieving the working line for each failure scenario. By constructing a protection line based on the above, construct an autonomous distributed control network that effectively suppresses the amount of equipment required for setting the protection line and realizes stable operation against equipment failure be able to.
[0013]
The SRLG notification means includes means for searching for SRLGs that can be backed up from information input from the backup possibility risk classification number management database, and an identification indicating that the search results of the means for searching are SRLG information that can be backed up Means for adding and publishing information, or the SRLG notifying means and means for searching for SRLG that cannot be backed up from information inputted from the backup possibility risk classification number management database. It is desirable to include means for adding the identification information indicating that the search result of the means is SRLG information that cannot be backed up, and notifying.
[0014]
In the former case, by calculating the route of the protection line only with the link suitable for accommodating the protection line, the route calculation of the protection line can be facilitated and only the SRLG that can be backed up is announced. Thus, an appropriate backup route can be searched by exchanging the minimum amount of information. In the latter case, it is possible to facilitate the route calculation of the protection line by excluding the link not suitable for accommodating the protection line from the route calculation of the protection line, and to advertise only the SRLG that cannot be backed up. This makes it possible to search for an appropriate backup route by exchanging a minimum amount of information.
[0015]
The three-party database is updated each time the network topology and the link usage state are changed, and the SRLG notification means is registered in the database every time the registration contents of the backup possibility / risk classification number management database change. It is desirable to provide means for notifying the other nodes of the SRLG information that has been made.
[0016]
In this way, by performing the announcement every time the database is updated due to the change of the link usage state and the network topology, it is possible to accurately set the protection line based on the highly accurate SRLG information.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The structure of the link state notification apparatus according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the link state notification device of this embodiment.
[0018]
This embodiment is a link state announcement device, and the feature of this embodiment is that, as shown in FIG. 3, the network topology and the link usage state are grasped based on the announcement from other nodes, and this grasp is obtained. Based on the network topology and link utilization state, provided in the node control unit 8 of a node that selects a transfer route of communication traffic passing through itself, and manages the bandwidth allocation state of the link to be managed based on the announcement. Link bandwidth allocation management database 1 and information on the shared standby bandwidth, which is a backup bandwidth capable of backing up a plurality of links set to the link in common, from this link bandwidth allocation management database 1 are input, and this shared spare bandwidth is backed up Backup risk classification number management data that manages the SRLG of the link through which the working path is passed Database 2, backup bandwidth classification management database 1 that searches and registers and manages SRLGs that can be backed up by the link from the link bandwidth allocation management database 1 and backup risk classification number management database 2, and this backup There is a notification function unit 4 for notifying other nodes of the SRLG information registered in the availability risk classification number management database 3.
[0019]
The route calculation unit 5 refers to the risk classification number which is SRLG recorded in the backup possibility risk classification number management database 3 and calculates the route of the working line and the protection line. The path setting unit 6 performs path setting by controlling the optical / electrical switch hardware 7 based on the route calculation result of the route calculation unit 5.
[0020]
The public notice function unit 4 searches for SRLGs that can be backed up from the information input from the backup possibility risk classification number management database 3, and adds the identification information indicating that the search results are SRLG information that can be backed up, and makes public notices. To do. Alternatively, the notification function unit 4 searches for SRLGs that cannot be backed up from the information input from the backup possibility risk classification number management database 3, and uses this search result as identification information indicating that the backup is not possible. In addition, public notice.
[0021]
The link bandwidth allocation management database 1, the backup risk classification number management database 2, and the backup availability risk classification number management database 3 are updated whenever the network topology and the link usage state are changed, and the notification function unit 4 determines whether the backup is possible or not. Whenever the registered contents of the classification number management database 3 change, risk classification number information, which is SRLG information registered in the database, is announced to other nodes.
[0022]
Hereinafter, this embodiment will be described in more detail.
[0023]
(First Example)
A first embodiment will be described with reference to FIGS. In the network of the present embodiment, each node implements a link state type routing protocol called OSPF or IS-IS protocol, and each node has a function of selecting a transfer route of communication traffic in an autonomous and distributed manner. . Each node that implements the routing protocol described above has a function of notifying adjacent nodes of the state information of each link connected to its own node, and such an operation is realized by each node in the network. Yes.
[0024]
That is, each node in the network can grasp the network configuration and the link state state of the entire network by collecting link state information repeatedly announced between the adjacent nodes. In the network of this embodiment, each link is an optical file, and each node is an optical router, which performs transfer processing in units of wavelength channels.
[0025]
What is characteristic in the network of the present embodiment is that one or a plurality of risk classification numbers are assigned to each link, and risk management such as equipment failure and link disconnection is performed for each link. The link state notification apparatus of the present invention is applied by being incorporated in a part of each node arranged in the network as described above.
[0026]
As shown in FIG. 3, the link status notification apparatus according to the present embodiment includes a link bandwidth allocation management database 1 that manages the usage status of a link to be managed, and an active backup that is backed up by a shared spare bandwidth set for the link. Backup risk classification number management database 2 for managing the risk classification number of the link through which the path passes, and backup for searching and registering the risk classification number that can be backed up by the link and the risk classification number that cannot be backed up from the two databases It is composed of a risk classification number management database 3 and a notification function unit 4 that inputs a risk classification number registered in the backup possibility risk classification number management database 3 and advertises it to other nodes. Has been implemented. The following description explains the operation of the link state notification device mounted on node number # 1.
[0027]
The link bandwidth allocation management database 1 manages the bandwidth usage status of each link accommodated in the node. 4 and 5 show the management status information of link # 4. The bandwidth usage status is managed by defining the status of active, spare, shared spare, free, and reserved. As shown in FIG. 5, in this embodiment, bands are managed in units of wavelength channels, λ1 to λ5 and λ8 are working bands, λ6 and λ7 are spare bands, λ9 to λ12 are shared spare bands, and λ13 is The reserved bandwidths λ14 to λ32 are free bandwidths.
[0028]
The spare band is defined as a 1: 1 correspondence with the working line and is a band in which resource reservation is performed. On the other hand, the shared spare band is used in a backup method for reserving resources for M channels of shared spare bands for N multiple active lines. The reserved bandwidth is a bandwidth that accommodates an optical path that is currently being set or deleted.
[0029]
The backup risk classification number management database 2 holds the risk classification number of the link through which the working optical path that uses the shared protection band defined for the link to be managed as a failure recovery means. That is, each node manages what risk classification number the working path belonging to which the shared protection band set in each link accommodated in the node is backing up. This is shown in FIGS.
[0030]
As described above, the entire shared spare band set for the link # 4 is a 2.5 Gbit / s optical path 4-wavelength channel, and the link of the risk classification number {12, 18, 21} using this shared spare band. 2.5 Gbit / s working optical paths #A, B, and C passing through the link, and the risk class number {12,15} links passing through the 2.5 Gbit / s working optical path #D and risk classification number { The working optical path #E having a bandwidth of 2.5 Gbit / s passing through the 11, 12} link is also backed up.
[0031]
It is inappropriate for the link # 4 in this state to newly back up the working optical path #F passing through the link of the risk classification number {12}. If the working optical paths #A to #E that have already passed the danger classification number {12} have been backed up, and the link of the danger classification number {12} has failed, the link can be made by simply backing up these working optical paths. The shared spare band of # 4 is used up. When the link with the danger classification number {12} fails, it is practically impossible to accommodate the working optical path #F in the link # 4. Therefore, it is necessary to search for another route that can back up the working optical path #F. The notification function unit 4 provides a key function for realizing such a function.
[0032]
In other words, it has a function of notifying other nodes of the risk classification number for which the link to be managed cannot be backed up. In other words, the notification function unit 4 refers to the management data as shown in FIG. 9 managed in the backup risk classification number management database 2 to extract the risk classification number that cannot be backed up. The identification information indicating that the risk classification number is a backup possible risk classification number list string is added and notified to the adjacent nodes # 2 and # 3.
[0033]
This information is notified to the entire network by hopping each node. On the contrary, similar information is notified from the adjacent node. FIG. 10 shows a format example of information notified to other nodes. It is composed of an overhead including information such as LinkID to be notified of information, a flag indicating that a risk classification number that cannot be backed up by this link is stored, and a payload storing the risk classification number.
[0034]
When setting the backup optical path of the working path #F passing through the risk classification number {12, 18, 21} through such information exchange, the route calculation is performed based on the network topology as shown in FIG. Become. The link # 4 that is notified that the danger classification number {12} cannot be accommodated is excluded from the route calculation target. Similarly, in the information notified from the other node, there is a notification that link # 5 cannot back up the working optical path passing through the link of the risk classification number {18, 21}. 5 is also excluded from the route calculation. Thus, according to the present invention, the backup optical path route calculation becomes extremely easy by excluding the link that is not suitable for accommodating the backup optical path from the backup optical path route calculation. In this embodiment, the protection path of the working optical path #F is # 1- # 2- # 5- # 7- # 8. At the same time, by notifying only the risk classification number that cannot be backed up, it is possible to search for an appropriate backup route by exchanging the minimum amount of information.
[0035]
(Second embodiment)
A second embodiment will be described with reference to FIGS. The configuration of the link state notification device of the second embodiment is the same as that of the first embodiment, and each node is implemented with a link state type routing protocol called OSPF or IS-IS protocol. It has a function of selecting a transfer path for communication traffic. The difference from the first embodiment lies in the node and the network to be applied, that the node is an IP router equipped with a multiprotocol label switching (MPLS) function and that the link is a 10 Gbit / s optical link. .
[0036]
The link bandwidth allocation management database 1 of the second embodiment also manages the bandwidth usage status of each link accommodated in the node. FIG. 13 shows the management status information of link # 5 shown in FIG. The bandwidth usage status is managed by defining the status of active, spare, shared spare, free, and reserved. As shown in FIG. 13, the link bandwidth allocation management database 1 in the second embodiment manages an optical link with a bandwidth of 10 Gbit / s connected to its own node. As shown in FIG. 13, 4.0 Gbit / s is a working band, 2.0 Gbit / s is a spare band, 3.0 Gbit / s is a shared spare band, and 0.1 Gbit / s is a reserved band (new LSP being set). 0.9 Gbit / s is a free band.
[0037]
The spare band is defined as a 1: 1 correspondence with the working line and is a band in which resource reservation is performed. Here, the line indicates a label switched path (LSP) defined in the framework of the multi-protocol label switching technology. That is, it is not a physical line but a logical line defined between MPLS routers.
[0038]
As in the case of the first embodiment, the backup availability risk classification number management database 3 stores the risk classification number of the link through which the working optical path that uses the shared spare band defined as the management target link as the failure recovery means. Possess. 14 and 15 show examples of information managed by the backup possibility / risk classification number management database 3. As shown in FIG. 14, working LSPs # 1 and # 2 having a bandwidth of 3.0 Gbit / s are Node # 2- # 3 and Nodes # 2- # 4 are working LSP # 3 having a bandwidth of 1.4 Gbit / s. The working LSP # 4 is set to Node # 1- # 4- # 5 in Node # 3- # 5.
[0039]
As shown in FIG. 15, the shared protection band of Link # 5 is a shared protection band for the working line that passes only the links having the risk classification numbers {101}, {102}, and {106}. The risk classification numbers {103} and {104} using the entire 3.0 Gbit / s band cannot be backed up.
[0040]
In this embodiment, a risk classification number that can be backed up as a management target link is announced to other nodes. That is, the notification function unit 4 extracts only the risk classification number that can be backed up by referring to the management data as shown in FIG. 15 managed in the backup risk classification number management database 2, and is the extracted information. The identification information indicating that the risk classification number is a list of risk classification number lists that can be backed up is added and notified to the adjacent nodes # 1, # 2, and # 5. This information is notified to the entire network by hopping each node.
[0041]
By performing such information exchange and performing the backup optical path route calculation using only the link accommodated by the backup optical path, the backup optical path route calculation becomes extremely easy. At the same time, by publishing only the risk classification number that can be backed up, it is possible to search for an appropriate backup route by exchanging the minimum amount of information.
[0042]
【The invention's effect】
As described above, according to the present invention, an autonomous decentralized control network that realizes stable operation against equipment failure while effectively suppressing the amount of equipment required for setting a protection line. It becomes possible to construct. At the same time, the amount of exchange information between nodes required for backup path route search can be reduced appropriately.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a technique for realizing the present invention.
FIG. 2 is a diagram for explaining means for solving problems to be solved by the present invention.
FIG. 3 is a block diagram of a link state notification device according to the present embodiment.
FIG. 4 is a diagram showing a network configuration example for explaining management state information according to the first embodiment;
FIG. 5 is a diagram showing management state information of the first embodiment.
FIG. 6 is a diagram showing a network configuration example for explaining backup risk classification number management according to the first embodiment;
FIG. 7 is a diagram showing an example of a link for explaining backup risk classification number management according to the first embodiment.
FIG. 8 is a diagram showing a correspondence relationship between a backup LSP_ID and a backup risk classification number according to the first embodiment.
FIG. 9 is a diagram showing an example of information managed by the backup risk classification number management table of the first embodiment.
FIG. 10 is a diagram showing a format example of information to be notified to other nodes in the first embodiment.
FIG. 11 is a diagram showing an example of a network topology for explaining the route calculation of the first embodiment.
FIG. 12 is a diagram showing an example of a network configuration for explaining management state information according to the second embodiment.
FIG. 13 is a diagram showing management status information according to the second embodiment.
FIG. 14 is a diagram showing an example of a network configuration for explaining an example of information managed by a backup possibility risk number classification management database according to the second embodiment;
FIG. 15 is a diagram showing an example of information managed in the backup possibility risk number classification management database of the second embodiment.
FIG. 16 is a diagram illustrating a conventional technique.
[Explanation of symbols]
1 link bandwidth allocation management database 2 backup risk classification number management database 3 backup possibility risk classification number management database 4 notification function section 5 route calculation section 6 path setting section 7 optical / electrical switch hardware

Claims (4)

Based on the announcement from the other node, the network topology and the link usage status are grasped, and the network traffic and the link usage status are grasped, and the node for selecting the transfer route of the communication traffic via the self is provided.
A link bandwidth allocation management database for managing a bandwidth allocation status of a link to be managed based on the announcement,
From this link bandwidth allocation management database, information on the shared spare bandwidth, which is a spare bandwidth capable of commonly backing up a plurality of links set for the link, is input, and the SRLG of the link through which the working path backed up by this shared spare bandwidth passes Backup risk classification number management database that manages (Shared Risk Link Group),
A backup possibility risk classification number management database that searches and registers and manages SRLGs that can be backed up by the link and SRLGs that cannot be backed up from the two databases;
A link state notification device comprising SRLG notification means for notifying other nodes of SRLG information registered in the backup possibility risk classification number management database. The SRLG notification means is:
Means for searching for SRLGs that can be backed up from information input from the backup possibility risk classification number management database;
The link state notification device according to claim 1, further comprising means for adding an identification information indicating that the search result of the means for searching is SRLG information that can be backed up. The SRLG notification means is:
Means for searching for SRLGs that cannot be backed up from information input from the backup possibility risk classification number management database;
2. The link state announcement device according to claim 1, further comprising means for making an announcement by adding identification information indicating that the search result of the means for searching is SRLG information that cannot be backed up. The three-party database is updated whenever the network topology and link utilization changes.
4. The SRLG announcement means according to claim 1, further comprising means for notifying other nodes of the SRLG information registered in the database every time a change occurs in the registration contents of the backup possibility risk classification number management database. The link status notification device described.

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